Field
Methods are described for reading and processing flow sensitive phase contrast magnetic resonance images to calculate and display dynamic flow parameters in a region of interest.
Description of the Related Art
Magnetic Resonance Imaging (“MRI”) refers to a medical imaging technique that utilizes strong magnetic fields to safely scan body tissues and generate two- and three-dimensional images of those tissues. Through the precise application of magnetic fields and radio signals, an MRI scan produces a series of image “slices” corresponding to planar regions of a three-dimensional scanned region, such as a subject's brain or chest cavity. Subsequent image processing generates high contrast images of internal body structures and tissues. In this way, MRI images enable physicians and clinicians to differentiate between different soft tissues within the body, such as brain, muscle, and heart tissue, as well as tumors and other diseased tissues.
Although MRI techniques and devices have been in use for many years, more recent technological developments have led to new and enhanced MRI methods. For example, Magnetic Resonance Angiography (“MRA”) is a modern technique that is capable of generating high contrast images of tissues that move over time, such as flowing blood. MRA techniques therefore enable physicians to visualize the anatomical structures of a subject's circulatory system, including the heart, arteries, and veins.
In some circumstances, relative movement of tissues within the scanning region, such as, for example, the swelling of an artery during cardiac systole, can have the effect of clouding the resulting MR image. One method to address this issue has been to inject a contrast agent into the subject's circulation to effectively highlight the moving tissues during an MRI scan of the subject. However, due to their chemical composition, injection of such contrast agents is undesirable. Phase contrast (“PC”) MRI techniques have been developed to address this issue. PC MRI techniques are capable of quantifying fluid flow by encoding velocity information into the phase of an MRI signal. Modern PC techniques can encode three-dimensional (“3D”) velocity data, along with signal intensity and temporal data, into a given MR image slice. In this way, PC MRI techniques account for the relative movement of soft tissues within the scanning region, and enhance the contrast of the resulting output image slices without the use of chemical agents.